Electromagnetic waves may be transferred from place to place through a conductor. In wired transmission, the conductor is usually a wire or other solid substance. In wireless transmission, the conductor is usually an ambient substance, such as air, water, etc. In wireless connections a transmitter is usually used to transfer a wave and a receiver to receive a wave. A transceiver combines the functions of both transmitter and receiver in one system. A transmitter typically converts electrical energy into a signal, which is then broadcast via an antenna to a receiver's antenna. Repeaters, middle stations, etc. may be used as intermediates in the transmission to sustain the integrity of the transmitted wave.
The electrical energy input into a transmitter usually is modulated into a basic transmission or carrier signal by overlaying some intelligence upon the energy—speech, data, etc.—in the form of an information signal, and the receiver typically demodulates the modulated carrier signal, once received, into a copy of the initial intelligence sent by the transmitter.
In order to accomplish their function, transmitters and receivers are comprised of various building block components. An electromagnetic information signal (which may be generated from the intelligence in any number of ways, e.g., by one or more transducers, such as a microphone, or received from a modulator, such as an analog modem) to be propagated may be modulated onto a carrier wave using a mixer, or modulator. The carrier wave itself is usually generated by an oscillator. An amplifier is usually used at one or more places in the transmitter circuitry to boost the signal strength, to provide power to active components, etc. Similarly, one or more filters are usually used as well, to clean up the input wave, the outputted signal, etc. An antenna is used to broadcast the signal, and a power supply will supply power as needed.
Various techniques may be used to actually transfer the intelligence. For example, electromagnetic waves representing the information signal in wireless transmission may be modulated into carrier waves by varying wave characteristics such as amplitude, frequency and phase, in an analog or digital manner.
One such mechanism for modulating an input signal is a digital phase modulator, in which a portion of the input signal, such as its phase information, may be digitized and used to modulate the phase of a carrier wave. In a digital phase modulator, a phase signal in the range of [−π,π] is called a wrapped phase, Φwrap(t). One characteristic of a wrapped phase is that it may have 2π discontinuities in phase that results large phase difference when used to modulate the carrier wave. However, the phase modulator requires smooth phase difference signal as its input.
For a digital phase modulator, an unwrapped phase signal gives a smooth waveform without the aforementioned 2π jumps in phase and results a better spectrum than a wrapped phase signal. However, an unwrapped phase signal is, in most cases, not bounded, and thus requires more bits to represents the unwrapped phase signal in a fixed-point implementation. Consequently, the unwrapped phase computation requires a larger die size and consumes more power.
It would be desirable to provide more efficient and precise transmitter, receiver and transceiver systems, methods and articles of manufacture, and particularly to provide a modulation system that uses a smaller die size and consumes less power, while improving accuracy and efficiency.